Measurement of the W+ W- cross section in pp collisions at sqrt(s) = 8 TeV and limits on anomalous gauge couplings

TL;DR

This paper reports a precise measurement of the W+W- production cross section at 8 TeV proton-proton collisions, compares it with Standard Model predictions, and sets limits on possible anomalous gauge couplings using effective field theory.

Contribution

It provides the first measurement of the W+W- cross section at 8 TeV with detailed differential analysis and constraints on anomalous gauge couplings in the effective field theory framework.

Findings

Measured W+W- cross section: 60.1 +/- 4.8 pb

Differential cross sections agree with perturbative QCD predictions

Set 95% CL limits on anomalous gauge couplings

Abstract

A measurement of the W boson pair production cross section in proton-proton collisions at sqrt(s) = 8 TeV is presented. The data collected with the CMS detector at the LHC correspond to an integrated luminosity of 19.4 inverse femtobarns. The W+W- candidates are selected from events with two charged leptons, electrons or muons, and large missing transverse energy. The measured W+W- cross section is 60.1 +/- 0.9 (stat) +/- 3.2 (exp) +/- 3.1 (theo) +/- 1.6 (lum) pb = 60.1 +/- 4.8 pb, consistent with the standard model prediction. The W+W- cross sections are also measured in two different fiducial phase space regions. The normalized differential cross section is measured as a function of kinematic variables of the final-state charged leptons and compared with several perturbative QCD predictions. Limits on anomalous gauge couplings associated with dimension-six operators are also given in the framework of an effective field theory. The corresponding 95% confidence level intervals are -5.7 < c[WWW]/Lambda^2 < 5.9 TeV^{-2}, -11.4 < c[W]/Lambda^2 < 5.4 TeV^{-2}, -29.2 < c[B]/Lambda^2 < 23.9 TeV^{-2}, in the HISZ basis.